Regulating system for maintaining electric converters at a constant speed



Aug. 14, 1928. 1,680,806

K. SCHMIDT REGULATING SYSTEM FOR MAINTAINING ELECTRIC CONVERTERS AT ACONSTANT SPEED Original Filed Jan. 15, 1924 IHVENTOR Karl schmidl'Patented Aug. 14, 1928.

UNITED STATES PATENT oFFi cE.

KARL SCHMIDT, OF BERLIN-'SUDENDE, GERMANY, ASSIGNOR TO 0. LORENZ AKTIEN-GESELLSCHAFT, OF BERLIN-TEMPELHOF, GERMANY.

REGULATING SYSTEM FOR MAINTAINING ELECTRIC CONVERTERS AT .A CONSTANTSPEED.

Original application filed January 15, 1924, Serial No. 686,432, and inGermany February 17, 1923. Divided and this application filed June 6,1925. Serial No. 35,501.

This invention relates to speed regulating,

systems for maintaining electric converters at a constant speed, andapplies particularly to speed regulating systems of that kind shown, forexample, in my prior application, Serial No. 686,432, filed January 15,1924, of which this application is a division, wherein a regulator isemployed in association with a dynamo, in contradistinction to the useof a relay, for controlling the speed of an electric motor whereby thedynamo is driven, such regulator being for the purposes of the .prcsentinvention, of suitable construction, but, in the form disclosed in saidapplica- 1 tion, Serial N 0. 686,432, comprising a resilient membersupporting a contact weight and mounted on' a vertically rotating diskcarrying a contact member, said contact ele ments operating under thecombined actions of centrifugal force and gravity once during eachrevolution of the disk to open and close a circuit whereby an electricalload is periodically imposed upon and withdrawn from the driving motorso as to control its speed and hold it at a constant value with such adegree of uniformity as is not possible with the speed regulatingdevices heretofore in use. The present invention premises the use of aregulator of such type or one acting equivalently for controlling a loadcircuit in a controlling system of the character herein described.

In the operation of electrical converters, it is known that the speed ofan electric motor can be maintained more or less constant by providing acentrifugal regulator with an electric contact and by causing thiscontact to influence the driving motor for regulation of its speed insome suitable way. In order to obtain a sulficiently sensitiveregulation, the load on the contact must be very small, that is to saythe contact is worked wit-h very weak currents; this however is in mostcases too small to influence the driving motor.

One or more relays must therefore be interposed; these however have, asis well known, such great disadvantages that it is impossible to obtaina reliable regulation of the driving motor. The object of the presentinvention is to avoid the use of such relays and to obtain a reliableregulation by making use of a dynamo instead of the relay, the

field of which dynamo is controlled by a pcriodlcal opening and closingof a contact of the speed regulator and the terminal voltage of which isapplied to the driving motor itself.

The invention is set forth more particularly by the followingdescription of some practical embodiments represented by theaccompanying drawings, of which Fig. 1 1s a diagram of connectionsshowing my invention as applied to the speed regulation of a directcurrent motor.

Figs. 2 and 3 refer to improvements of a system accordingto Fig. 1,

Fig. 4 is a diagram showing how the invention may be practiced inconnection with a three-phase motor.

Similar reference characters refer to similar elements-throughout thedrawings.

F igure 1 of the accompanying drawing illustrates the principle of thearrangement according to the present invention. The set of a highfrequency converter comprises a high frequency generator k which isdriven by a continuous current motor m and on the end of the shaft ofwhich there is mounted a centrifugal regulator provided with a contactdevice is. This contact device is is so controlled by centrifugal forceand by a force acting in opposition thereto, that a periodic opening andclosing of the contact is effected during the rotation of thecentrifugal regulator. The contact is arranged to open and close aresistance r in a well-known manner by the interposition of slip-rings sand to act on a source of continuous current 9 supplying the excitationwinding 6 of the dynamo d of a converter which is driven by the motorm,. The armature terminals of the dynamo d are connected to theexcitation windingn of the motor m,. It will easily be seen that verysmall currents in the regulating circuit or in the excitation winding 6of the dynamo d will be capable of controlling a substantial energy.

nother arrangement according to the invention is illustrated in Figure 2in which the dynamo d is mounted on the shaft of the converter, theexcitation winding n being connected to the supply circuit and to oneterminal of the dynamo.

According to a further modification of the invention the motor m isprovided with two windings as is illustrated in Figure 3. The motor m isprovided with the excitation Winding n and in addition thereto withanother excitation Winding n which is connected to the terminals of thedynamo. A particular advantage of this arrangement lies therein that themotor has a permanent, constant, fundamental field and the danger of themotor running away is avoided.

Figure l illustrates, by way of example, the diagram of a converter inwhich a threephase motor m is used as the driving motor. In thisarrangement the regulating machine d controls the alternating currentchokes (Z d d inserted in the stator winding of the motor to change theapplied terminal voltage through the continuous current windlngs 1 2!g3:

at I clalm 1s:

1. In a speed regulating system for electric converters, a drivingmotor, a regulating generator, a circuit including a "source of electricenergy and the exciter wlnding of the generator, the said generatorbeing operatively connected to the exciter winding of the driving motorfor controlling the excitation of said motor, and means directlygoverned by the speed of the driving motor for energizing anddeenergizing said circuit at predetermined motor speeds.

2. In a speed regulating system for electric converters, a driving motorforming part of said converter, a regulating generator, a circuitincluding a source of electric energy and the exciter Winding ofthegenerator, the said generator having its terminals directly connected tothe exciter Winding of the driving motor for controlling the excitationof said motor, and means independent of the A. C. output of saidconverter and governed by the speed of the driving motor for energizingand deenergizing said circuit at predetermined motor speeds.

3. In a speed regulating system for electric converters, a driving motorfor said converter, a regulating generator, a circuit including a sourceof electric energy and the exciter winding of the generator, the saidgenerator being operatively connected to the exciter winding of thedriving motor for controlling the excitation of said motor, and acentrifugal contact device governed by the speed of the driving motorfor energizing and deenergizing said circuit at predetermined motorspeeds.

4. In a speed regulating system for electric converters, a driving motorfor saidconverter, a regulating dynamo, a circuit including a source ofelectric energy and the exciter winding of the dynamo, the said dynamohaving its terminals directly connected to the exciter winding of thedriving motor for controlling the excitation of said motor, and acentrifugal contact device independent of any circuit forming part ofthe load on said motor and governed by the speed of the driving motorfor energizing and deenergizing said circuit at predetermined motorspeeds.

5. In a speed regulating system for electric converters, a drivingmotor, a regulating dynamo, a circuit including a source of electricenergy and the exciter winding of the dynamo, the said dynamo beingoperatively connected to the exciter winding of the driving motor forcontrolling the excitation of said motor, said driving motor excitingwinding being independent of said source of current, and a centrifugalcontact device on the shaft of the driving motor governed by the speedof the driving motor for energizing and deenergizing said circuit atpredetermined motor speeds.

6. In a speed regulating system for electric converters, a drivingmotor, a direct current regulating dynamo, a circuit including a sourceof electric energy independent of the armature of the regulating dynamobut including the exciter winding of the dy namo, the said dynamo havingits armature terminals directly connected to 'theexciter winding of thedriving motor for controlling the excitation of said-motor, and acentrifugal contact device on the shaft of the driving motor governed bythe speed of the driving motor for energizing and deenergizing saidcircuit at predetermined motor I electric energy and the exciter windingof the dynamo, the said dynamo having its terminals directly connectedto theexciter winding of the driving motor for controlling theexcitation of said motor, and a centrifugal contact device on the shaftof the driving motor governed by the speed of the driving motor forenergizing and deenergizing said circuit at predetermined motor speeds.

8. In a speed regulatorsystem for an electric-motor comprising incombination a rotating disc driven bysaid motor, a resilient membermounted on said disc and carrying a contact arranged to be opened andclosed with respect to a contact carried by said disc, means foreffecting contact once for each revolution of said disc, the ratiobetween the open and closed periods of time of said contact beingsubstantially dependent said resistance, said d amo field circuit beingindependent of said motor exciter wind- In a speed regulator system foran electric motor comprising in combination a 1'0- tating disc driven bysaid motor, a resilient member mounted on said 'disc and carrying acontact arranged to be opened and closed with respect to a contactcarried by said disc, means for effecting contact once for eachrevolution of said disc, the ratio between the relative lengths of timeduring which the.

contact is opened and closed being substantially dependent on the speed,a regulating dynamo operatively connected to the exciter Winding of saidmotor, and driven by said electric motor, and an electric resistance inthe field circuit of said dynamo and a circuit connection from saidcontacts to the terminals of said resistance.

10. In a speed-regulator system for an electric motor comprising incombination a rotating disc driven by said motor a resilient membermounted on said disc an carrying a contact arranged to be opened andclosed with respect to a contact carried by said disc, means forefiecting contact once for each revolution of said disc, the ratiobetween the closed and open periods of said contact being substantiallydependent on the speed, a regulating dynamo having its terminalsdirectly connected to the exciter winding of said motor and driven bysaid electric motor, and an electric resistance in the field circuit ofsaid dynamo and a circuit connection from said contacts to the terminalsof said resistance.

In testimony whereof I have signed my name to this specification.

K. SCHMIDT.

